MSK

Question 1

Periostitis without underlying bone lesion

Answer 1

• trauma
• hypertrophic pulmonary osteoarthropathy
• venous stasis
• thyroid acropachy
• pachydermoperiostosis

Question 2

Ddx for lytic epiphyseal lesion

Answer 2

• giant cell tumor
• chondroblastoma
• infection
• geode

Question 3

Posterior elements expansile lesion in a young person

Answer 3

• osteoblastoma (internal mineralisation)
• ABC (no internal mineralisation)

Question 4

Epiphyseal overgrowth ddx (skeletally immature)

Answer 4

Chronic inflammation from:
- hemophilia related hemarthrosis
- juvenile rheumatoid arthritis

Question 5

Diffusely increased bone density

Answer 5

• metabolic disorders eg primary hyperparathyroidism, hypervitaminosis D, fluorosis
• osteoblastic mets eg breast, prostate, pancreas, TCC, lymphoma, medulloblastoma, neuroblastoma
• hematologic - myelofibrosis, mastocytosis, sickle cell infarcts
• Paget’s blastic phase
• osteopetrosis

Question 6

Polyostotic fibrous dysplasia

Answer 6

• McCune Albright syndrome: café au lait coast of Maine spots, endocrinopathy eg precocious puberty
• Mazabraud syndrome: adjacent intramuscular myxomas

Question 7

Lytic bone metastases ddx

Answer 7

‘LyTiK’
- lung
- thyroid
- Kidney

AND the nonspecific lytic / blastic mets:
- breast
- stomach
- colorectal

Question 8

Blastic metastases ddx

Answer 8

‘Below the diaphragm’
- prostate
- seminoma
- mucinous tumor
- carcinoid

And the nonspecific lytic/blastic (BSC)
- breast
- stomach
- colorectal

Question 9

Vertebra plana ddx

Answer 9

(i MELT)
- infection (osteomyelitis / tuberculosis)
- metastases
- eosinophilic granuloma (LCH)
- lymphoma (multiple levels), leukemia (kids)
- trauma

Also
- hemangioma
- osteoporosis / osteogenesis imperfecta

Question 10

Platyspondyly ddx

Answer 10

flattened vertebral bodies throughout the axial skeleton
- severe Gaucher disease
- Morquio syndrome
- osteogenesis imperfecta
- thanatophoric dysplasia
- acromegaly

Question 11

Ivory vertebra ddx

Answer 11

M.PHIL
- Metastases (prostate, breast, etc) and myelofibrosis
- Paget disease of bone
- hemangioma
- Infection (tuberculous spondylitis)
- Lymphoma, usually Hodgkin
- fluorosis
- chordoma

Pediatric
- lymphoma, usually Hodgkin
- osteosarcoma
- osteoblastoma
- neuroblastoma
- medulloblastoma
- Ewing sarcoma (rare)

Question 12

Lytic dental lesion ddx

Answer 12

• periapical cyst (a/w caries, <1cm, near root)
• dentigerous cyst (around crown)
• odontogenic keratocyst (strong assoc w/Gorlin-Goltz aka basal cell nevus syndrome)
• Amyloblastoma
• eosinophilic granuloma (maxilla/mandible floating tooth)

Question 13

Lytic calcaneal lesion ddx

Answer 13

• intraosseous lipoma (may have calcification)
• simple bone cyst (no sclerosis)
• aneurysmal bone cyst (sclerotic margin)
• pseudolesion (trabecular atrophy)

Question 14

Acro-osteolysis ddx

Answer 14

CHOP FINger

C: collagen vascular disease, e.g. scleroderma, Raynaud disease
H: hyperparathyroidism
O: other, e.g. polyvinyl chloride exposure
P: psoriasis/pyknodysostosis/progeria
F: familial, e.g. Hajdu-Cheney syndrome
I: injury, e.g. thermal burn, frost bite
N: neuropathy, e.g. diabetes mellitus, leprosy
ger: no dx